La mémoire diminue toute seule

Bonjour,
J'ai un problème sur mon ordi depuis environ 1 semaine. Tout d'abord la mémoire de mon disque dur, qui a une capacité de 500 Go, diminuait à chaque redémarrage d'environ 2 Go alors que je ne sauvegardais rien de spécial sur mon ordi. J'ai donc fait un scan minutieux Avast, un scan Spybot et un scan windows defender. Rien n'a été trouvé. Puis quand je redémarais mon ordi la mémoire ne diminuais plus, je pensais que le problème était résolu. Cependant je viens d'avoir un problème : j'étais en train d'installer des mises à jours via windows update lorsque l'ordi a eu un blue screen et s'est redémmaré. Au redémarrage la mémoire du disque dur avait diminué de 10 Go, de plus sur internet les icones des sites sont inversées. Je ne sais plus quoi faire : j'ai supprimé les cookies, les fichiers temporaires, j'ai nettoyé le registre avec ccleaner... Je vous met donc un rapport d'HijackThis :

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 20:05:46, on 08/04/2008
Platform: Windows Vista (WinNT 6.00.1904)
MSIE: Internet Explorer v7.00 (7.00.6000.16609)
Boot mode: Normal

Running processes:
C:\Windows\system32\taskeng.exe
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Program Files\Common Files\LogiShrd\LVCOMSER\LVComSer.exe
C:\Program Files\Windows Defender\MSASCui.exe
C:\Program Files\Alwil Software\Avast4\ashDisp.exe
C:\Program Files\Java\jre1.6.0_05\bin\jusched.exe
C:\Program Files\Common Files\Logishrd\LComMgr\Communications_Helper.exe
C:\Program Files\Logitech\QuickCam\Quickcam.exe
C:\Windows\System32\rundll32.exe
C:\Windows\SOUNDMAN.EXE
C:\Program Files\Windows Sidebar\sidebar.exe
C:\Windows\ehome\ehtray.exe
C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
C:\Program Files\RocketDock\RocketDock.exe
C:\Program Files\Logitech\Desktop Messenger\8876480\Program\LogitechDesktopMessenger.exe
C:\Program Files\Logitech\SetPoint\SetPoint.exe
C:\Windows\System32\mobsync.exe
C:\Program Files\Windows Media Player\wmpnscfg.exe
C:\Windows\ehome\ehmsas.exe
C:\Windows\System32\rundll32.exe
C:\Program Files\Common Files\Logishrd\KHAL2\KHALMNPR.EXE
C:\Program Files\Windows Sidebar\sidebar.exe
C:\Program Files\Windows Sidebar\sidebar.exe
C:\Program Files\Windows Mail\WinMail.exe
C:\Program Files\Common Files\Logishrd\LQCVFX\COCIManager.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Program Files\Common Files\Microsoft Shared\Windows Live\WLLoginProxy.exe
C:\Users\Nemo\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\C9ELVCI2\HiJackThis[1].exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.google.fr/?gws_rd=ssl
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = https://www.msn.com/fr-fr/?ocid=iehp
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.msn.com/fr-fr/?ocid=iehp
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = *.local
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
R3 - URLSearchHook: Yahoo! Toolbar avec bloqueur de fenêtres pop-up - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - (no file)
O1 - Hosts: ::1 localhost
O2 - BHO: Yahoo! Toolbar Helper - {02478D38-C3F9-4efb-9B51-7695ECA05670} - (no file)
O2 - BHO: Aide pour le lien d'Adobe PDF Reader - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: Spybot-S&D IE Protection - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_05\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
O2 - BHO: Windows Live Sign-in Helper - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Common Files\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar1.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\2.1.1119.1736\swg.dll
O2 - BHO: InlineSearchHandleHotKeys Class - {B6FFE2AE-4D12-451F-B457-FE6125FFB1CF} - C:\Program Files\IEForge\Inline Search\InlineSearch.dll
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar1.dll
O4 - HKLM\..\Run: [Windows Defender] %ProgramFiles%\Windows Defender\MSASCui.exe -hide
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [Kernel and Hardware Abstraction Layer] KHALMNPR.EXE
O4 - HKLM\..\Run: [Logitech Hardware Abstraction Layer] KHALMNPR.EXE
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.6.0_05\bin\jusched.exe"
O4 - HKLM\..\Run: [Adobe Reader Speed Launcher] "C:\Program Files\Adobe\Reader 8.0\Reader\Reader_sl.exe"
O4 - HKLM\..\Run: [LogitechCommunicationsManager] "C:\Program Files\Common Files\LogiShrd\LComMgr\Communications_Helper.exe"
O4 - HKLM\..\Run: [LogitechQuickCamRibbon] "C:\Program Files\Logitech\QuickCam\Quickcam.exe" /hide
O4 - HKLM\..\Run: [NvSvc] RUNDLL32.EXE C:\Windows\system32\nvsvc.dll,nvsvcStart
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\Windows\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\Windows\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [NBKeyScan] "C:\Program Files\Nero\Nero8\Nero BackItUp\NBKeyScan.exe"
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\VistaCodecPack\QT\QTTask.exe" -atboottime
O4 - HKCU\..\Run: [Sidebar] C:\Program Files\Windows Sidebar\sidebar.exe
O4 - HKCU\..\Run: [ehTray.exe] C:\Windows\ehome\ehTray.exe
O4 - HKCU\..\Run: [SpybotSD TeaTimer] C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
O4 - HKCU\..\Run: [RocketDock] "C:\Program Files\RocketDock\RocketDock.exe"
O4 - HKCU\..\Run: [WMPNSCFG] C:\Program Files\Windows Media Player\WMPNSCFG.exe
O4 - HKCU\..\Run: [IndxStoreSvr_{79662E04-7C6C-4d9f-84C7-88D8A56B10AA}] "C:\Program Files\Common Files\Nero\Lib\NMIndexStoreSvr.exe" ASO-616B5711-6DAE-4795-A05F-39A1E5104020
O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /detectMem (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-19\..\Run: [WindowsWelcomeCenter] rundll32.exe oobefldr.dll,ShowWelcomeCenter (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /detectMem (User 'SERVICE RÉSEAU')
O4 - HKUS\S-1-5-18\..\Run: [Picasa Media Detector] C:\Program Files\Picasa2\PicasaMediaDetector.exe (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [Picasa Media Detector] C:\Program Files\Picasa2\PicasaMediaDetector.exe (User 'Default user')
O4 - Global Startup: Logitech Desktop Messenger.lnk = C:\Program Files\Logitech\Desktop Messenger\8876480\Program\LogitechDesktopMessenger.exe
O4 - Global Startup: Logitech SetPoint.lnk = C:\Program Files\Logitech\SetPoint\SetPoint.exe
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_05\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_05\bin\ssv.dll
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\Office12\REFIEBAR.DLL
O9 - Extra button: (no name) - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O9 - Extra 'Tools' menuitem: Spybot - Search & Destroy Configuration - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O13 - Gopher Prefix:
O16 - DPF: {56762DEC-6B0D-4AB4-A8AD-989993B5D08B} - https://www.eset.com/
O16 - DPF: {867E13F2-7F31-44FB-AC97-CD38E0DC46EF} (HardwareDetection Control) - https://www.touslesdrivers.com
O18 - Protocol: bwfile-8876480 - {9462A756-7B47-47BC-8C80-C34B9B80B32B} - C:\Program Files\Logitech\Desktop Messenger\8876480\Program\GAPlugProtocol-8876480.dll
O22 - SharedTaskScheduler: Windows DreamScene - {E31004D1-A431-41B8-826F-E902F9D95C81} - C:\Windows\System32\DreamScene.dll
O23 - Service: Apple Mobile Device - Apple, Inc. - C:\Program Files\Common Files\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashServ.exe
O23 - Service: avast! Mail Scanner - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
O23 - Service: avast! Web Scanner - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
O23 - Service: Service Bonjour (Bonjour Service) - Apple Inc. - C:\Program Files\Bonjour\mDNSResponder.exe
O23 - Service: Canon Camera Access Library 8 (CCALib8) - Canon Inc. - C:\Program Files\Canon\CAL\CALMAIN.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files\Common Files\InstallShield\Driver\1050\Intel 32\IDriverT.exe
O23 - Service: Logitech Bluetooth Service (LBTServ) - Logitech, Inc. - C:\Program Files\Common Files\Logitech\Bluetooth\LBTServ.exe
O23 - Service: LiveUpdate - Symantec Corporation - C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
O23 - Service: LVCOMSer - Logitech Inc. - C:\Program Files\Common Files\LogiShrd\LVCOMSER\LVComSer.exe
O23 - Service: Process Monitor (LVPrcSrv) - Logitech Inc. - C:\Program Files\Common Files\LogiShrd\LVMVFM\LVPrcSrv.exe
O23 - Service: LVSrvLauncher - Logitech Inc. - C:\Program Files\Common Files\LogiShrd\SrvLnch\SrvLnch.exe
O23 - Service: Nero BackItUp Scheduler 3 - Nero AG - C:\Program Files\Nero\Nero8\Nero BackItUp\NBService.exe
O23 - Service: NMIndexingService - Nero AG - C:\Program Files\Common Files\Nero\Lib\NMIndexingService.exe
O23 - Service: Norton Ghost - Symantec Corporation - C:\Program Files\Norton Ghost\Agent\VProSvc.exe
O23 - Service: O&O Defrag - O&O Software GmbH - C:\Windows\system32\oodag.exe
O23 - Service: PLFlash DeviceIoControl Service - Prolific Technology Inc. - C:\Windows\system32\IoctlSvc.exe
O23 - Service: SBSD Security Center Service (SBSDWSCService) - Safer Networking Ltd. - C:\Program Files\Spybot - Search & Destroy\SDWinSec.exe

End of file - 10158 bytes

Merci de votre aide